1. Field of the Invention
The invention concerns a hydrodynamic coupling and particularly the line that conducts the working medium inside the hydrodynamic coupling.
2. Description of Related Art
Hydrodynamic couplings are known. A particular field of application is in the area of turbocompound systems, in which an exhaust gas turbine is disposed in a drive train in the exhaust gas flow of an internal combustion engine and is in a driven connection with the crankshaft. In such systems, in the driven connection between the exhaust gas turbine and the crankshaft, a hydrodynamic coupling is advantageously connected in order to transfer power or torque, respectively. If the primary impeller of such a hydrodynamic coupling is driven by the exhaust gas turbine, this turbine, via the flow circuit for working medium in the working chamber of the hydrodynamic coupling, drives the secondary impeller of the hydrodynamic coupling, which is usually connected to the crankshaft by means of a suitable gear. This first driving mode is also referred to as the turbocoupling mode.
As long as the hydrodynamic coupling is equipped with a means for locking the primary impeller resistant to rotation, the hydrodynamic coupling may also be used in a second mode—a retarder mode—for braking the crankshaft. In this mode, the secondary impeller is driven by the crankshaft, the primary impeller is locked resistant to rotation, for example, by means of a multiplate coupling, and the crankshaft is braked by the transfer of torque from the secondary impeller to the primary impeller. Based on the fact that in one case (turbocoupling mode), the primary impeller is driven, and in the other case (retarder mode), the secondary impeller is driven, the direction of the flow of circulating working medium is opposite for the two cases. Therefore, the direction of axial thrust varies, a fact which must be taken into consideration in the design of the bearing and the shaft seals.
In addition, the rpm ranges are different in the turbocoupling mode and in the retarder mode. Overall, there usually results an rpm range between 4000 rpm and 12,000 rpm. The inlet and outlet seals, i.e., the seals with which the channels introducing the working medium and the channels discharging the working medium are sealed, are operated in this rpm range. In all relative seals, i.e, in seals between the components, when one of these rotates at a different rpm than the other and when one rotates and the other does not rotate, there is the problem, in particular, that two distinct operating ranges are present. Therefore, relative seals are conventionally designed in the form of an expensive floating ring seal. Such a floating ring seal is comparatively expensive and sensitive to disruption.